That’s a very specific promise, with a timeline attached. And it is a promise that no President has the power to fulfill.

If we elide the distinction between prisons (holding people convicted of serious crimes) and jails (holding people convicted of minor crimes and people awaiting trial), it is true and important that the U.S. leads the world in incarceration. That’s a disgrace. (I seem to recall having written a book on the topic.)

We should do something about that, and there are things to do about it. A President can do some of them.

But of the 2.3 million people behind bars in this country, fewer than 10% are Federal prisoners. The rest are in state prisons and local jails. If the President were to release all of the Federal prisoners, we would still, as a country, have more prisoners than any other country. So Sen. Sanders was very specifically making a promise he has no way of keeping. Either he knows that or he does not.

And his promise to accomplish it with “education and jobs” utterly misunderstands the short-term relationships between schooling and employment on the one hand and crime and incarceration on the other.

So it sounds as if Sen. Sanders, after several decades in public office, is either utterly unserious or utterly clueless about the crime issue. Again, that’s excusable. But since he also seems to know very little about foreign policy, and much of what he thinks he knows about health care is just plain wrong, someone might want to start asking what it is he does know about, other than how to get a crowd riled up by denouncing the banksters.

Those of us supporting Hillary Clinton this year are sometimes accused of wanting to settle for political small-ball rather than sweeping change. But no matter how good Sen. Sanders’s intentions may be, he’s not going to be able to change very much for the better unless he’s willing to learn something about the way the world, and the political system, actually operate.

Learning requires both humility – the knowledge of what one does not now know – and curiosity. Sen. Sanders’s passionate conviction that he already knows the truth, and that anyone who disagrees with him must be in the pay of special interests, does not suggest that he numbers either humility or curiosity among his many virtues.

It’s been clear for years that requiring homeless people to subdue their mental illness or kick their drug habits or otherwise become model citizens before being sheltered failed utterly to reduce their misbehavior but succeeded splendidly in increasing the duration of their exposure to the elements.Â What a surprise: without a roof under which to sleep or a safe place to store one’s stuff, other life changes become damn near impossible.

The same logic should apply to any program of reentry from prison or jail: before discharging a prisoner, corrections officials should make sure that s/he has a place to live, and provide one (albeit minimal) if not.Â In other words, treat people who are homeless because they’ve been locked up the same as people who are homeless for any other reason.Â This means recognizing that, without a stable place to live, staying out of trouble with the law becomes one of those damn near impossible life changes.Â And that’s without even considering the people incarcerated precisely because they’re homeless—because “The law, in its majestic equality, forbids the rich as well as the poor to sleep under bridges, to beg in the streets, and to steal bread.”

It’s costly to provide housing.Â But just as scholars and practitioners finally figured out that it was cheaper to house people than to keep shuttling them between the streets and the emergency rooms, I suspect we’ll soon find that it’s cheaper to house those who’ve made it out of the criminal justice system than it is to keep sending them back in.

I hereby submit my nomination for the most underreported public policy story of the past year: The continuing decline in the number of Americans who are behind bars or on probation/parole. Both the change itself and low level of attention it has garnered are worthy of reflection.

At the time of President Obama’s inauguration, the incarceration rate in the United States had been rising every single year since the mid 1970s. The relentless growth in the proportion of Americans behind bars had persisted through good economic times and bad, Republican and Democratic Presidents, and countless changes in state and local politics around the country.

If a public policy trend with that much momentum had even slowed significantly, it would have been merited attention, but something far more remarkable occurred: The incarceration rate and the number of people under correctional supervision (i.e., including people on probation/parole) declined for three years in a row. At the end of 2011, the proportion of people under correctional supervision returned to a level not seen since the end of the Clinton Administration.

You’d think this would be big news, but it’s gone largely unnoticed. Indeed, if you google on news articles and op-eds about incarceration that have appeared during the Obama Administration, you will find precious few that mention or even seem aware of the change. John Tierney dropped some breadcrumbs in his recent NYT article, which I hope means he will delve into the decline in incarceration as his series of articles on criminal justice progresses. There’s a great deal a good journalist could illuminate for the public, for example which policies and politics are producing the change and how it plays out on the ground.